The present invention pertains to an improved post assembly for a buried valve and more particularly is a valve indicator and operator post assembly with means for displaying valve position that may be operatively connected to a buried or otherwise remotely located fluid control valve with or without a mechanical valve actuator.
In subsurface fluid distribution systems, such as water mains and supply pipes for fire suppression systems, it is often necessary to place manually operable control valves in locations that are remote from a manual access point. For instance many commercial buildings have water supply lines direct from outside water mains which lines are dedicated to automatic sprinkler networks and controlled solely from one or more points outside the buildings. Control is by means of one or more valves such as butterfly valves, buried with the water line below frost level. Normally the valve is positioned in, or biased to, the open position and a mechanical valve actuator is connected to the valve shaft or stem to enable a human attendant to close and reopen the valve as may be needed when inspecting and servicing the system. A mechanical valve actuator is simply a mechanically advantaged machine such as worm levers gears or skotch yoke which enables the attendant to apply sufficient torque to move the valve between open and closed positions.
Often an indicator is provided at the access point to display the position of the valve to facilitate routine inspections. The mechanical actuator may be located at the valve or at the access point with various advantages and disadvantages attendant to each choice. However where the mechanical actuator has been buried with the valve it has often been the practice to separately couple the indicator to the valve apart from the mechanical connection needed to drive the valve actuator. This is due in part to a need to weather proof the indicator mechanism. However in at least one prior device combining an indicator with a drive stem to a buried valve actuator the drive stem terminates as a nut extending through a seal in a permanently fixed cover.
In some instances, such as with a buried gate valve, there is no need for a mechanical actuator and the drive stem may be connected directly with a threaded shaft that raises and lowers the gate. Nevertheless in such instances there is need for an indicator and operator post assembly.
Also in prior devices the indicators have been difficult to read in that they have been viewable from only limited angles and have not been highly visible even in daylight. Prior indicators have been of two general forms, one being a target movable either vertically or rotary within a post to display "open" or "closed" signs within view windows in the post; and the other movable rotary to block sight through two opposite windows, when the valve is closed, and to open sight through opposite windows when the valve is open. The latter is believed to be more visible and readily identified from a distance during daylight as the valve is known to be open when background light is seen through a window. However the view angle is limited and even where two pairs of opposed windows have been utilized they have been located at different post elevations which has resulted in loss of visibility from diagonal locations and under poor light conditions.
In one prior device combining an indicator and drive stem an indicator target has vertically spaced "open" and "closed" signs on two faces which are viewable through two 180.degree. separated windows in a round post. The target slides on two guides within the post and is driven by threads at the upper part of the drive stem which is turned by an operating nut which extends through a seal in a permanently secured cap on the post. A wrench may be locked onto a side of the post between the windows, and the wrench may have a portion that overlies the operating nut to make it unavailable to unauthorized persons.
Prior valve post assemblies have been securely fastened to the buried valve housing and had to be stocked in several lengths to accommodate the wide range of depths at which valves may be buried. This has resulted in added inventory expense; and caused problems of supply and selection in the field where the proper post assembly has to be connected upon placing a valve in a given system. Also prior post assemblies have been susceptible to damage, or damage to the valve and/or valve actuator, resulting from either excessive torque or impact force being transmitted to the valve. When this has occurred it has often required the entire post assembly and valve to be exhumed for servicing.